Treat initial-scratch-message as a doc string

* doc/emacs/building.texi (Lisp Interaction):
* doc/lispref/os.texi (Startup Summary):
* etc/NEWS: Document this.
* lisp/startup.el (initial-scratch-message):
Look up find-file’s key rather than hardcoding it.
(command-line-1): Substitute the doc string.
This also substitutes the quotes, which will help test display
quoting at startup.

2 files changed, 3 insertions, 2 deletions

diff --git a/doc/emacs/building.texi b/doc/emacs/building.texi
index b4a99a1c25e..1d40a2dd12d 100644
--- a/doc/emacs/building.texi
+++ b/doc/emacs/building.texi
@@ -1549,7 +1549,7 @@ mode are the same as in Emacs Lisp mode.
   At startup, the @file{*scratch*} buffer contains a short message, in
 the form of a Lisp comment, that explains what it is for.  This
 message is controlled by the variable @code{initial-scratch-message},
-which should be either a string, or @code{nil} (which means to
+which should be either a documentation string, or @code{nil} (which means to
 suppress the message).
 
 @findex ielm
diff --git a/doc/lispref/os.texi b/doc/lispref/os.texi
index 64ebb45f23b..bbe87ca6181 100644
--- a/doc/lispref/os.texi
+++ b/doc/lispref/os.texi
@@ -195,7 +195,7 @@ It now exits if the option @code{--batch} was specified.
 
 @item
 If the @file{*scratch*} buffer exists and is empty, it inserts
-@code{initial-scratch-message} into that buffer.
+@code{(substitute-command-keys initial-scratch-message)} into that buffer.
 
 @item
 If @code{initial-buffer-choice} is a string, it visits the file (or
@@ -314,6 +314,7 @@ file will not inhibit the message for someone else.
 
 @defopt initial-scratch-message
 This variable, if non-@code{nil}, should be a string, which is
+treated as documentation to be
 inserted into the @file{*scratch*} buffer when Emacs starts up.  If it
 is @code{nil}, the @file{*scratch*} buffer is empty.
 @end defopt